Part 1—Review frog calling date data.
Part 2— Evaluate changing temperatures
Part 3 — Extrapolate findings to expected changes in the future
(note: these instructions also included in the student worksheet)
Part 1 - Review Frog Calling Data
Frog calling data is summarized in the MS Excel spreadsheet (Amphibian Data File.xlsx). Data is available for each year for 1900-1912. For the decade of the 1990s, the information is provided only as a decadal average. Data are missing for some frogs and some years.
- Open the MS Excel spreadsheet, and the tab for “Frog Calling Dates."
- Determine average and standard deviations for the 1900-1912 data to compare to the 1990-2000 averages. The standard deviation is a measure of the year-to-year variability in calling dates that would be attributed to variations in the weather. Differences in the dates between the early and late 19th century can be attributed more to changes in climate.
- Create a graph to illustrate the differences in calling dates.
- What general trends do you see in the frog calling dates between the two periods of time?
- For each of the frog types, evaluate if the change (number of days) in calling dates between the two periods is greater than the variation (standard deviation) within a decade.
- Choose one type of frog with significant changes in the dates of their mating calls for further study (note – the teacher may assign these)
Part 2 - Evaluate Changing Temperatures
Monthly average daily temperatures are included for the 20th century in the MS Excel workbook. These data are also easily available from the NASA GISS web tool, which allows access to annual and monthly temperature data. Follow your teacher’s instructions regarding using data already in the spreadsheet or downloading the data from the NASA GISS website. For more details, see the tutorial for instructions for accessing and downloading data for the Ithaca, NY weather station.
- Open the MS Excel spreadsheet – “Avg. Monthly Temp” spreadsheet page. (or see the Excel data file you created)
- Using your knowledge of phenology concepts, write a hypothesis regarding the temperatures that might be related to the starting dates of the mating calls. This could be the average temperature for a month or a season.
- For the temperature defined in your hypothesis, calculate the average temperature over the time periods of interest (1900-1912 and 1900-2000). Compare these values. How much does the temperature change over the 20th century?
- Plot the date of the start of the mating calls as a function of the monthly or seasonal average temperature. Fit a linear equation to these two data points.
Part 3 - Extrapolate Findings to Expected Changes in the Future
Scientists predict that the temperature in New York State will continue to rise throughout the 21st century. The predictions of the possible temperature rise depend on the expectations of how our populations will grow and technologies developed over this time period. Mathematical models of our climate were used to predict temperature in New York State. The results are available through the Northeast Climate Data Center. Predictions are provided for two cases. The A1 scenario is the worst case and B1 a less severe case, with expectations that we take a global and environmentally oriented approach to developing over the next century. Use the tutorial for the Northeast Climate Data Center web site to review maps of projected temperatures for the end of the 21st century in New York State.
- Open the Northeast Climate Data Center web site and register as a user (remember your user name and password!)
- See the graphic below (or the tutorial): Select New York State (1) and geographic plot (2); the temperature (3) and month or season (4) you determined to be the best indicator of the starting date for your frog mating call, and the time period of interest (2070-2099) (5). Click on “plot new parameters” (6) to create new charts for review.
- Use the color scale to estimate the future temperature for the Ithaca region (7) and record the temperature for both the A1 (worse case) and B1 (better case) modeling scenarios. Raw data for each year are also available and included in the MS Excel spreadsheet (“Predictive Temperatures A1” and “Predictive Temperatures B1”.
- Use the projected future temperatures and your linear equation to extrapolate and predict the amphibian calling date at the end of the 21st century. Record the date for both the A1 and B1 climate prediction models.
- Discussion Questions:
- How much will the calling dates change (# days) between the early and late decades of the 21st century. How do these changes compare to the changes over the 20th century. Discuss why these values may be different.
- What impact do you think these projected changes will have on frog viability in this region and ecosystem health? What other information about frog habitat and climate conditions do you think would be needed to evaluate frog viability in this region?
- If we see this type of impact with the frogs what other fauna or flora could be sensitive to increases in average temperatures and how might they adapt?
- What are the potential errors in your approach and analysis? Discuss the values and limitations of your work?
Materials for Activities:
Lecture Support Materials:
Links to External Resources: